Android Question How to test if object variable is an Activity?

Discussion in 'Android Questions' started by qsrtech, Jun 2, 2015.

  1. qsrtech

    qsrtech Active Member Licensed User

    I thought

    if obj is activity then
    end if
    but it doesn't work. Any other way to test if "obj" is an activity?


    For now I've resorted to using a try/catch/finally until a better way is established
    Last edited: Jun 2, 2015
  2. LucaMs

    LucaMs Expert Licensed User

    If GetType(obj) = "android.widget.FrameLayout" Then IsActivity = True
    DonManfred likes this.
  3. qsrtech

    qsrtech Active Member Licensed User

    hmmm. idk if I did something wrong but the activity is coming up as "java.lang.Class"
  4. Erel

    Erel Administrator Staff Member Licensed User

    You can use this code:
    Sub IsActivity(obj As Object) As Boolean
    If Not(obj Is PanelThen Return False
    Dim jo As JavaObject = obj
    Dim parent As Object = jo.RunMethod("getParent"Null)
    Return parent <> Null And (GetType(parent) = "android.widget.FrameLayout" Or _
    GetType(parent) = "anywheresoftware.b4a.objects.IME$ExtendedBALayout")
    End Sub
    LucaMs, klaus and DonManfred like this.
  5. LucaMs

    LucaMs Expert Licensed User

    This means that the Module Scale should be updated, given that my answer is part of it ;)
  6. Erel

    Erel Administrator Staff Member Licensed User

    Not sure that I understand???
  7. LucaMs

    LucaMs Expert Licensed User

    My code, post #2, is part of Module Scale; if it is not correct, we should (must) replace it with yours.
  8. Erel

    Erel Administrator Staff Member Licensed User

    Your code as it is, is not clear. What is obj? I guess that you copied a small part of a larger code snippet. So it is impossible to say whether it is correct or not.
  9. LucaMs

    LucaMs Expert Licensed User

    Erel, my obj is the @qsrtech's obj :)

    and in Module Scale there is:
    Public Sub IsActivity(v As ViewAs Boolean
    Dim obj As Object
        obj = GetParent(v)
    If GetType(obj) = "android.widget.FrameLayout" Then
    Return True
    Return False
    End If
    End Sub
  10. Erel

    Erel Administrator Staff Member Licensed User

    The code you now posted is 99% correct (though you still didn't post the GetParent sub).
    The only case where it will not work is if someone uses IME.AddHeightChangedEvent.
  11. LucaMs

    LucaMs Expert Licensed User

    I did not need of GetParent !

    @qsrtech required only if OBJ is an Activity.
  12. Erel

    Erel Administrator Staff Member Licensed User

    You need to understand how the code works...

    It tests the object parent to see whether it is a frame layout or not. The activity itself is the same native object as a panel.
  13. LucaMs

    LucaMs Expert Licensed User

    Well I'm lost, and I can say: "luckily" :D

    because you can use:

    but you can not use:
    where SecondActivity should be an activity object, but it is only a class!

    Please, do not answer or I will be forced to go to study Android + Java + Eclipse and then seek a mental hospital still open :p
  14. LucaMs

    LucaMs Expert Licensed User

    Well, if obj (#1) is an activity object, "is activity" works.

    Sub Activity_Create(FirstTime As Boolean)
    Activity.AddView(pnl, 0050dip50dip)
    Dim Parent As Object = GetParent(pnl)
    If Parent Is Activity Then
    End If

    End Sub
    Sub GetParent(v As ViewAs Object
    Dim jobj = v As JavaObject
    Return jobj.RunMethod("getParent"Null)
    End Sub
  15. qsrtech

    qsrtech Active Member Licensed User

    I think it's because the parent is the actual activity you are calling it in. I suspect it won't work if the "parent" is from another activity. Anyway, i'm moving away from using multiple activities within in an app. I mainly needed this piece of code temporarily while testing. I would encourage others to do the same, especially to make your app more ready for other platforms. Another benefit is you can make use of a drawer much easier. Now if we could only get a template feature it would sure help in the process. Btw, how's things going with you? You probably noticed i was absent for quite a while. B4i kinda pulled me back in ;)
  16. LucaMs

    LucaMs Expert Licensed User

    The problem is that I have already forgotten a lot 'of things :D.

    When you use "Me" or an Activity name, for example StartActivity(...), the parameter is a class name, not an object, instance of an Activity.

    You can use another Activity but obj must "contain" an Activity, not its class name.

    I think that rarely you can use one Activity only, without going crazy with dozens of views and panels.

    I should answer with a not nice word, like sht, but I can't :p

    So, welcome back :)
  17. qsrtech

    qsrtech Active Member Licensed User

    Actually it's quite easy and more flexible. You simply convert your activity to a class and have a panel within that class that you load your layout into. I'll post a skeleton class when i get to my comp. In your main activity you simply handle the showing/hiding of the form classes. It's basically how you need to do it in b4i so it's better to do it in b4a as well. Another benefit is you can create multi windows a lot easier. A good example would be spreadsheet pages.

    I think i'll create a navigation class like the one in b4i to handle all the "page" stuff in b4a. Then it's just a matter of a few conditionals and b4a apps are pretty much ready for b4i. There's a great tool to significantly help convert b4a layouts to b4i. (Just wish it was a more drag and drop tool vs cmd line) Of course android is far superior to ios but unfortunately with around 30% of the market share i have no choice but to support it.

    Thanks :)

    Edit: I should add with classes vs activities, you don't have all the issues of recreating you activity everytime you switch between them (and saving state)
  18. LucaMs

    LucaMs Expert Licensed User

    Good, become a B4i expert, so when I have released an Android app (2059 :D), I will ask you to convert it to iOS.

    ... and write in the Main Activity all the code needed for "each Activity", including events. Uhm... mumble mumble :rolleyes:
    RandomCoder likes this.
  19. qsrtech

    qsrtech Active Member Licensed User

    No silly, all the events are handled within the class. You only call back the main activity if you need to, probably not much different than what you do now with inter-activity stuff.
  20. LucaMs

    LucaMs Expert Licensed User

    Sorry, I can not see the benefits.

    Let's see if I understood.

    You have the Activity Main, in which you declare x number of classes, we could call them "Activity classes".

    Then, at any given time, you use that class and show its layout within a panel.

    The class is generic, it does not contain specific code, so all the app code is contained in the Main Activity.

    Is it so?
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